MACK TRUCKS CAMPAIGN NO N/A.WITH SN56 AND SW57 BOGIE HOUSINGS.BUILT MAR1971 THRU JUN 1972.TRUCKS.POSSIBILITY THAT THE BOGIE HOUSING WALL THICKNESSAT THE LEFT INNER WHEEL BEARING RACE MAY NOT MEET SPECIFIC DIMENSIONALREQUIREMENTS.IF THIS CONDITION EXISTS, IT COULD LEAD TO SPINDLE FAILURE,RESULTING IN LOSS OF A REAR WHEEL ASSEMBLY.(CORRECT BY INSPECTING ANDREPLACING BRGIE HOUSING WHERE NECESSARY).